Re: [xml-dev] Why are erroneous ENTITY declarations not caught in XML validation?

On 23/10/2012 11:29, David Carlisle wrote:

 > ...

another interesting feature is that in an entity declaration after a & 
the following characters have to match the productions for entity or 
character references (including a trailing colon) even though the 
entities may not be used, so...


<!DOCTYPE x [
<!ENTITY foo "<![CDATA[ &hhh; ]]>" >
<!ELEMENT x (#PCDATA)*>
]>
<x>&foo;</x>


is well formed and valid, use of the reference to foo does not result in 
an error, it is equivalent to:

<x> &amp;hhh; </x>


However if you remove the ; to get

<!DOCTYPE x [
<!ENTITY foo "<![CDATA[ &hhh ]]>" >
<!ELEMENT x (#PCDATA)*>
]>
<x>&foo;</x>


The result is not well formed:

$ rxp -xV  ent.xml
Error: Expected ; after entity name, but got <space>


the use of & within an entity declaration has to be syntactically a 
reference, even though if expanded the & would not start a reference as 
it would be quoted by the CDATA declaration.

David





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